/*
 * Copyright 2008-2009 the original 赵永春(zyc@hasor.net).
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package net.hasor.search.utils;
import java.io.IOException;
import java.text.DateFormat;
import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Calendar;
import java.util.Collection;
import java.util.Date;
import java.util.Iterator;
import java.util.Locale;
import java.util.TimeZone;
/**
 * This class has some code from HttpClient DateUtil.
 */
public class DateUtil {
    //start HttpClient
    /**
     * Date format pattern used to parse HTTP date headers in RFC 1123 format.
     */
    public static final String              PATTERN_RFC1123              = "EEE, dd MMM yyyy HH:mm:ss zzz";
    /**
     * Date format pattern used to parse HTTP date headers in RFC 1036 format.
     */
    public static final String              PATTERN_RFC1036              = "EEEE, dd-MMM-yy HH:mm:ss zzz";
    /**
     * Date format pattern used to parse HTTP date headers in ANSI C
     * <code>asctime()</code> format.
     */
    public static final String              PATTERN_ASCTIME              = "EEE MMM d HH:mm:ss yyyy";
    //These are included for back compat
    private static final Collection<String> DEFAULT_HTTP_CLIENT_PATTERNS = Arrays.asList(PATTERN_ASCTIME, PATTERN_RFC1036, PATTERN_RFC1123);
    private static final Date               DEFAULT_TWO_DIGIT_YEAR_START;
    static {
        Calendar calendar = Calendar.getInstance(TimeZone.getTimeZone("GMT"), Locale.ROOT);
        calendar.set(2000, Calendar.JANUARY, 1, 0, 0);
        DEFAULT_TWO_DIGIT_YEAR_START = calendar.getTime();
    }
    private static final TimeZone           GMT                          = TimeZone.getTimeZone("GMT");
    //end HttpClient
    //---------------------------------------------------------------------------------------
    /**
     * A suite of default date formats that can be parsed, and thus transformed to the Solr specific format
     */
    public static final Collection<String>  DEFAULT_DATE_FORMATS         = new ArrayList<String>();
    static {
        DEFAULT_DATE_FORMATS.add("yyyy-MM-dd'T'HH:mm:ss'Z'");
        DEFAULT_DATE_FORMATS.add("yyyy-MM-dd'T'HH:mm:ss");
        DEFAULT_DATE_FORMATS.add("yyyy-MM-dd");
        DEFAULT_DATE_FORMATS.add("yyyy-MM-dd hh:mm:ss");
        DEFAULT_DATE_FORMATS.add("yyyy-MM-dd HH:mm:ss");
        DEFAULT_DATE_FORMATS.add("EEE MMM d hh:mm:ss z yyyy");
        DEFAULT_DATE_FORMATS.addAll(DEFAULT_HTTP_CLIENT_PATTERNS);
    }
    /**
     * Returns a formatter that can be use by the current thread if needed to
     * convert Date objects to the Internal representation.
     *
     * @param d The input date to parse
     * @return The parsed {@link java.util.Date}
     * @throws java.text.ParseException If the input can't be parsed
     */
    public static Date parseDate(String d) throws ParseException {
        return parseDate(d, DEFAULT_DATE_FORMATS);
    }
    public static Date parseDate(String d, Collection<String> fmts) throws ParseException {
        // 2007-04-26T08:05:04Z
        if (d.endsWith("Z") && d.length() > 20) {
            return getThreadLocalDateFormat().parse(d);
        }
        return parseDate(d, fmts, null);
    }
    /**
     * Slightly modified from org.apache.commons.httpclient.util.DateUtil.parseDate
     * <p/>
     * Parses the date value using the given date formats.
     *
     * @param dateValue   the date value to parse
     * @param dateFormats the date formats to use
     * @param startDate   During parsing, two digit years will be placed in the range
     *                    <code>startDate</code> to <code>startDate + 100 years</code>. This value may
     *                    be <code>null</code>. When <code>null</code> is given as a parameter, year
     *                    <code>2000</code> will be used.
     * @return the parsed date
     * @throws ParseException if none of the dataFormats could parse the dateValue
     */
    public static Date parseDate(String dateValue, Collection<String> dateFormats, Date startDate) throws ParseException {
        if (dateValue == null) {
            throw new IllegalArgumentException("dateValue is null");
        }
        if (dateFormats == null) {
            dateFormats = DEFAULT_HTTP_CLIENT_PATTERNS;
        }
        if (startDate == null) {
            startDate = DEFAULT_TWO_DIGIT_YEAR_START;
        }
        // trim single quotes around date if present
        // see issue #5279
        if (dateValue.length() > 1 && dateValue.startsWith("'") && dateValue.endsWith("'")) {
            dateValue = dateValue.substring(1, dateValue.length() - 1);
        }
        SimpleDateFormat dateParser = null;
        Iterator formatIter = dateFormats.iterator();
        while (formatIter.hasNext()) {
            String format = (String) formatIter.next();
            if (dateParser == null) {
                dateParser = new SimpleDateFormat(format, Locale.ROOT);
                dateParser.setTimeZone(GMT);
                dateParser.set2DigitYearStart(startDate);
            } else {
                dateParser.applyPattern(format);
            }
            try {
                return dateParser.parse(dateValue);
            } catch (ParseException pe) {
                // ignore this exception, we will try the next format
            }
        }
        // we were unable to parse the date
        throw new ParseException("Unable to parse the date " + dateValue, 0);
    }
    /**
     * Returns a formatter that can be use by the current thread if needed to
     * convert Date objects to the Internal representation.
     *
     * @return The {@link java.text.DateFormat} for the current thread
     */
    public static DateFormat getThreadLocalDateFormat() {
        return fmtThreadLocal.get();
    }
    public static TimeZone               UTC            = TimeZone.getTimeZone("UTC");
    private static ThreadLocalDateFormat fmtThreadLocal = new ThreadLocalDateFormat();
    private static class ThreadLocalDateFormat extends ThreadLocal<DateFormat> {
        DateFormat proto;
        public ThreadLocalDateFormat() {
            super();
            //2007-04-26T08:05:04Z
            SimpleDateFormat tmp = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss.SSS'Z'", Locale.ROOT);
            tmp.setTimeZone(UTC);
            proto = tmp;
        }
        @Override
        protected DateFormat initialValue() {
            return (DateFormat) proto.clone();
        }
    }
    /** Formats the date and returns the calendar instance that was used (which may be reused) */
    public static Calendar formatDate(Date date, Calendar cal, Appendable out) throws IOException {
        // using a stringBuilder for numbers can be nice since
        // a temporary string isn't used (it's added directly to the
        // builder's buffer.
        StringBuilder sb = out instanceof StringBuilder ? (StringBuilder) out : new StringBuilder();
        if (cal == null)
            cal = Calendar.getInstance(TimeZone.getTimeZone("GMT"), Locale.ROOT);
        cal.setTime(date);
        int i = cal.get(Calendar.YEAR);
        sb.append(i);
        sb.append('-');
        i = cal.get(Calendar.MONTH) + 1; // 0 based, so add 1
        if (i < 10)
            sb.append('0');
        sb.append(i);
        sb.append('-');
        i = cal.get(Calendar.DAY_OF_MONTH);
        if (i < 10)
            sb.append('0');
        sb.append(i);
        sb.append('T');
        i = cal.get(Calendar.HOUR_OF_DAY); // 24 hour time format
        if (i < 10)
            sb.append('0');
        sb.append(i);
        sb.append(':');
        i = cal.get(Calendar.MINUTE);
        if (i < 10)
            sb.append('0');
        sb.append(i);
        sb.append(':');
        i = cal.get(Calendar.SECOND);
        if (i < 10)
            sb.append('0');
        sb.append(i);
        i = cal.get(Calendar.MILLISECOND);
        if (i != 0) {
            sb.append('.');
            if (i < 100)
                sb.append('0');
            if (i < 10)
                sb.append('0');
            sb.append(i);
            // handle canonical format specifying fractional
            // seconds shall not end in '0'.  Given the slowness of
            // integer div/mod, simply checking the last character
            // is probably the fastest way to check.
            int lastIdx = sb.length() - 1;
            if (sb.charAt(lastIdx) == '0') {
                lastIdx--;
                if (sb.charAt(lastIdx) == '0') {
                    lastIdx--;
                }
                sb.setLength(lastIdx + 1);
            }
        }
        sb.append('Z');
        if (out != sb)
            out.append(sb);
        return cal;
    }
}